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. Author manuscript; available in PMC: 2012 Apr 1.
Published in final edited form as: Curr Opin Struct Biol. 2011 Apr;21(2):223–231. doi: 10.1016/j.sbi.2011.01.006

Figure 2.

Figure 2

Structure and assembly of microcompartment shells. BMC shell proteins (top) form hexamers that constitute the main building blocks of the shell. These assemble further to form tightly packed layers with pores in the middle of the hexamers, some of which have gated openings. BMC shell proteins are found widely across the bacteria. Where they occur, they provide a signature for the presence of a microcompartment organelle. In the carboxysome, pentameric proteins (CcmL and CsoS4) likely form the vertices of the shell, which is nearly icosahedral in shape (lower left). Pdu microcompartments and some other types form less geometrically regular shells (lower right) from hexameric BMC proteins; the presence of pentameric shell proteins in those cases has not been established.